What is the use of filter contexts in Power BI measures?

Filter contexts are crucial in Power BI because they dictate the specific subset of data that is considered during DAX (Data Analysis Expressions) calculations within measures. When measures are evaluated, they incorporate the active filters from the report, such as those applied through slicers, visual interactions, or row/column contexts in tables.

This means that the calculations performed in measures are not static; they dynamically respond to the filters applied in the report. For example, if a measure is designed to calculate total sales and there is a filter applied to show sales for a specific region, the measure will only compute the total sales for that region. This behavior is foundational for creating interactive and meaningful reports in Power BI, as it allows users to drill down and analyze data from various perspectives based on the filters they choose.

Considering the other choices, they do not directly relate to the primary function of filter contexts. The data model structure and visual formatting are essential components of a report but are not determined by filter contexts. Similarly, while exporting data to Excel is a feature in Power BI, it is unrelated to how filter contexts function within measures. This is why understanding filter contexts is integral to leveraging measures effectively in Power BI.